The main clinical purpose of Four Dimensional Magnetic Resonance Imaging (4D MRI) is treatment margin definition for external beam radiation therapy. Normally, 4D MRI data acquisition methods are based on usage of sensor signals indicative of the state/phase of the motion to be resolved. E.g. in respiratory 4D MRI a respiratory belt or MRI based navigators are used to detect a requested motion state and to trigger the acquisition.
However, especially in the abdominal region, motion can be composed of periodic and singular motion and the respective motion space to be covered is a-priori less known, e.g. in some regions peristaltic motion may outweigh the respiratory motion (e.g. pelvis) while in others respiratory motion will be predominant (e.g. upper abdomen). As a consequence, utilization of one motion sensor is often insufficient for treatment planning, since a more comprehensive measurement of the motion statistics is desirable. An additional disadvantage of classical 4D MRI is the strongly decreasing scan efficiency towards the end of the scan and the resulting bio-feedback.
United States Patent Application publication US 2012/0281897 A1 discloses a method for reducing, in an image, motion related imaging artifacts includes obtaining an image dataset of a region of interest, generating a plurality of intermediate images using the image dataset, applying a multivariate data analysis technique to the plurality of the intermediate images to generate motion information, sorting the intermediate images into a plurality of bins based on the motion information, and generating an image of the region of interest using at least one of the plurality of bins.